As it happens, Art of Problem Solving questions actually fit the bill of being really difficult. Most chapters have about 15 or so "challenge" problems, of which 5 or so are really hard.
The scoring system I used was to (a) give myself double points for answering the really hard challenge problems, and (b) only require a total score of 10 for all the challenge problems combined. So if I got all the regular problems correct + 10 points on the challenge problems (1 point per "standard" challenge problem and 2 points per "hard" challenge problem) then I'd score 100. One side effect of this was that on chapters with a particularly large number of challenge problems it was possible to get something like a 140. But in any case, getting a 100 actually wasn't that easy.
Your job, should you choose to accept it, is to comment on this thread explaining the most awesome thing you've done this month. You may be as blatantly proud of yourself as you feel. You may unabashedly consider yourself the coolest freaking person ever because of that awesome thing you're dying to tell everyone about. This is the place to do just that.
Remember, however, that this isn't any kind of progress thread. Nor is it any kind of proposal thread. This thread is solely for people to talk about the awesome things they have done. Not "will do". Not "are working on". Have already done. This is to cultivate an environment of object level productivity rather than meta-productivity methods.
So, what's the coolest thing you've done this month?